Moderate

When round and yellow color seeded plant (RrYy) is self-crossed the number of plants with rounds and yellow color seeds obtained is _ in 32 plants:

Correct answer: A. 18

  • A. 18
  • B. 9
  • C. 3
  • D. 1

Explanation

Option A is correct.When a round and yellow seeded plant (RrYy) is self-crossed, the expected phenotypic ratio of the offspring is 9:3:3:1. In this ratio, 9 represents the plants with round and yellow seeds. To find the number of these plants in a total of 32, you can calculate:(9/16) * 32 = 18.This indicates that out of 32 plants, we expect 18 to exhibit the round and yellow phenotype. The other options are incorrect because they do not accurately reflect the expected ratios from a dihybrid cross. Option B (9) represents only a fraction of the expected round and yellow plants; Option C (3) and Option D (1) both underestimate the number of plants based on the Mendelian inheritance ratios. Thus, they do not align with the expected outcomes of the genetic cross.

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About Inheritance

Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.

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